Methionine and cystine requirements of slow- and fast-feathering male broilers from zero to three weeks of age.

Auburn University, Poultry Science, Auburn, Alabama 36849, USA.
Poultry Science (Impact Factor: 1.54). 10/2003; 82(9):1423-7. DOI: 10.1093/ps/82.9.1423
Source: PubMed

ABSTRACT Two experiments were conducted with fast- (Ross x 3F8) and slow- (Ross x 308) feathering broiler males from 0 to 3 wk of age to determine Met and Cys requirements. A corn-soybean meal basal diet was formulated to be deficient in Met and Cys but was adequate in all other nutrients (22.0% CP; 3,050 kcal ME/kg). In experiment 1, diets contained 0.50% dietary Cys with 0.35, 0.40, 0.45, and 0.50% total Met. Feed conversion (FC) of slow- and fast-feathering males improved in a similar manner to 0.50% Met (linear, P < 0.05). Nitrogen retention measured from 20 to 21 d of age optimized at 0.46% Met (quadratic, P < 0.01), regardless of feathering rate. Experiment 2 examined the response to feeding 0.35, 0.40, 0.45, and 0.50% total Cys in diets having total Met at 0.45%. Increasing Cys improved FC that optimized at 0.40% with fast-feathering birds (quadratic, P < 0.01), whereas slow-feathering broilers were not responsive. Nitrogen retention measured from d 20 to 21 did not indicate a difference attributable to feathering but a Cys optimization at 0.43% with both broiler sources. Present experimentation indicates a Met requirement approximating 0.50% is appropriate for broilers 0 to 3 wk of age, regardless of feather rate; however, the estimated Cys requirement for slow-feathering males (0.39%) was less than for fast-feathering (0.44%) males.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The following paper reviews the current data regarding the physiological origins of variations in feed efficiency, and the effects of genetic selection on energy balance parameters. Effects of diet composition on response to genetic selection are considered by focusing on three feed factors: protein concentration, energy concentration and utilisation of specific ingredients. Analyses of effects of genetic selection on responses to diet composition highlight the problems associated with the increased dietary protein concentrations needed by the latest commercial broilers as a result of genetic selection. The advantages and disadvantages in producing lean birds are discussed from the point of view of feed efficiency and adaptation to feed variation. Lastly, the problems of variation in digestibility resulting from broiler selection are discussed.
    World's Poultry Science Journal 08/2008; 64(03):377 - 390. DOI:10.1017/S004393390800010X · 1.16 Impact Factor
  • The Journal of Applied Poultry Research 01/2008; 17(1):157-167. DOI:10.3382/japr.2007-00071 · 0.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Summary Transition cows must exquisitely coordinate their metabolism to meet tremendous increases in nutrient demand during early lactation, particularly the demand for glucose production by liver. Excessive mobilization of nonesterified fatty acids (NEFA) from body fat during the transition period presents challenges to liver function, including the capacity of liver to produce glucose. Strategies to either reduce the supply of NEFA to the liver or optimize the metabolism of NEFA by liver include maximizing dry matter intake of well-formulated transition rations, dietary supplementation with choline, or short-term drenching strategies using propylene glycol. Supplementation of other nutrients (methionine analogs and conjugated linoleic acid) has been shown to improve performance during early lactation; however, their mode of action does not appear to be related directly to liver metabolism. Research investigating nutritional grouping strategies for dry cows indicates that the two-group dry cow system is preferred to a one-group dry cow system; however, there may be interactions of grouping system with body condition score on postpartum performance.

Full-text (2 Sources)

Available from
Jan 22, 2015